1. Field of the Invention
The present invention relates to a front rail in a sub-rack, which acts as a cabinet in which a plurality of printed circuit boards packing electronic circuit assemblies are mountable, and which constitutes an electronic equipment unit such as a communication apparatus and so on.
2. Description of the Prior Art
FIG. 1 is a perspective view of the constitution of a conventional sub-rack. In FIG. 1, reference numeral 100 denotes a sub-rack. 101 denotes a top plate. 102 denotes a bottom plate. 103 denotes a side plate. 104 denotes a front rail arranged on front edges of the top plate 101 and the bottom plate 102, respectively. 105 denotes a mid-rail arranged on a midrange of the top plate 101 and the bottom plate 102, respectively, so as to cross the midrange. 106 denotes a guide rail whose both ends are mounted on upper faces of the front rail 104 and the mid-rail 105. 107 denotes a locating hole for locating a position on which a printed circuit board (not shown) is inserted.
FIG. 2 is a perspective view of the sub-rack 100 that a plug-in unit is partially mounted. In FIG. 2, 111 denotes a front panel constituting a front part of the sub-rack 100 when the printed circuit board (not shown) is mounted into the sub-rack 100. 112 denotes a handle mounted on the front panel 111 and used for the insertion of the printed circuit board (not shown) into the sub-rack 100 and for the removal thereof from the sub-rack 100. FIG. 3 is a side view of the constitution of the plug-in unit mounted into the sub-rack 100. In FIG. 3, since the common numerals denote common elements or the counterparts in FIG. 2, the description of such parts is omitted. 121 denotes a printed circuit board. 122 denotes a connector arranged on the printed circuit board 121, which is connectable by a plug-in type with another connector (not shown) on a back plane mounted on a rear part of the sub-rack 100. 123 denotes a guide pin which can be inserted into the locating hole 107 in order to locate the printed circuit board 121. 124 denotes a handle-supporting part which is connected with the printed circuit board 121 or the front panel 111. 125 denotes a pin which is fixed to the handle 112 or the handle-supporting part 124 to allow rotation of the handle 112 with respect to the handle-supporting part 124.
FIG. 4 is a drawing of the plug-in unit coupling with the front rail. In FIG. 4, since the common numerals denote common elements or the counterparts in FIGS. 1 to 3, the description of such parts is omitted. 131 denotes a first claw part of the handle 112, and 132 denotes a second claw part of the handle 112. 133 denotes a first engagement part formed on the front rail 104, and 134 denotes a second engagement part formed on the front rail 104.
The operation of this invention will be described as follows.
When the plug-in unit having the printed circuit board 121 is inserted into the sub-rack, the printed circuit board 121 is slid along a groove formed in the guide rail 106. The guide pin 123 arranged on the plug-in unit is then inserted into the locating hole 107 formed in the front rail 104 to locate the front panel 111 with respect to the front rail 104. Consequently, the handle 112 is rotated in a direction xe2x80x9cAxe2x80x9d in a state of engaging the first claw part 131 of the handle 112 with the first engagement part 133 of the front rail 104. The connector 122 of the printed circuit board 121 is then connected to the back plane to finish the insertion of the plug-in unit into the sub-rack 100.
When the plug-in unit is removed from the sub-rack 100, the handle 112 is rotated in a direction xe2x80x9cBxe2x80x9d in a state of engaging the second claw part 132 of the handle 112 with the second engagement part 134 of the front rail 104 to remove the connector 122 of the printed circuit board 121 from the back plane. Consequently, the printed circuit board 121 is pulled out along the groove formed in the guide rail 106 to remove the plug-in unit from the sub-rack 100.
The conventional sub-rack is constituted as described above. The front rail 104 is made of extruded aluminum materials. When a plurality of large-size printed circuit boards are mounted on the front rail 100, the front rail 100 bent, and the printed circuit board 121 disconnects from the groove of the guide rail 106 and falls to the bottom part of the sub-rack 100.
Accordingly, it is an object of the present invention to provide a front rail having a sufficient strength to hold a plurality of large-size printed circuit boards in required positions of a sub-rack.
In order to achieve the object of the present invention, a front rail in a sub-rack formed by bending a plate comprises a front part having a hole, the hole allowing insertion of a dowel pin, the dowel pin being arranged on a printed circuit board, a top part on which a guide rail for guiding the printed circuit board is mounted, a rear part extending from the top part via a hem formed by folding back a plate, the rear part for supporting a lower portion of the top part, and a bottom part extending from the rear part. As a result of such a pressing operation of one steel sheet and the arrangement of the hem, the front rail can obtain a sufficient strength. As a result, the front rail is hardly bent when the plurality of large-size printed circuit boards are mounted thereon, and it can prevent such boards from dropping out of the guide rail.
Here, the front part may come into contact with the bottom part the hem. The structural strength of the front rail can be therefore enhanced by the addition of the hem. It is easy to form the hem extending from the top part because the front part extends from the bottom part. Accordingly, the production of the front rail is facilitated.
The front rail may further comprise a plurality of engagement holes which are arranged on the hem extending from both the front and bottom parts. The claw part of the handle of the plug-in unit can easily engage with the engagement hole, and convenience of operation can be enhanced.
The front rail may further comprise a mounting part having a screw hole, the mounting part formed by bending a cantilever part in a lateral direction, wherein the cantilever part is integrated with the top part. The front rail can be therefore easily arranged in the sub-rack owing to a simple operation of connecting a bolt inserted into the side part of the sub-rack with the screw hole.
The front rail may further comprise a mounting part having a screw hole, the mounting part formed by bending a cantilever part in a lateral direction, wherein the cantilever part is integrated with the bottom part. Since the side parts of the sub-rack can sustain the downward load forcing on the bottom part to prevent the hem extending from the top part from opening, the stability of the front rail shape can be improved. Accordingly, aspects such as a positioning accuracy can be further improved.
The front rail may further comprise a mounting hole arranged on the hem extending from the top part, the mounting part for mounting a guide rail guiding the printed circuit board. Accordingly, it is possible to form the mounting hole by a series of sheet-metal processes including bending and so on. When compared with arranging a mounting member on the top part by another operation steps, the front rail in embodiment 1 can be manufactured at a low cost.
The front rail may further comprise a plurality of projections arranged on the rear edge side, the respective projections extending in a rear direction. The guide rail guiding the printed circuit board can be therefore mounted on the projections by forwardly moving the guide rail in a horizontal direction. Accordingly, the mounting of the guide rail on the front rail can be easily performed, and the structure of a guide rail-mounting part can be simplified which facilitates manufacture of the front rail. Since the guide rail is mounted relative to the projections, positional accuracy of the guide rail can be further improved.
The front rail may further comprise a screw-accommodating part formed by partially cutting and raising an articulated region defined between the rear part and the bottom part, and a female screw thread cut in an internal face of the screw-accommodating part. The front rail can be therefore easily arranged in the sub-rack by the simple operation of connecting the bolt inserted into the side part of the sub-rack with the screw hole formed at the screw-accommodating part. Since the screw-accommodating part is formed by only a cutting and raising operation, the structure of a guide rail-mounting part can be simplified which facilitates manufacture of the front rail.
A pole-type body may be inserted into a cavity partitioned by the front, the top, the rear and the bottom parts, the pole-type body having a height nearly equal to a distance between the top and the bottom parts. The structural strength of the front rail can be therefore enhanced because the pole-type body functions as a reinforcing member.
The front rail may further comprise a plurality of insertion holes formed in the pole-type body. The respective insertion holes allow dowel pins to be inserted. Since it is not necessary to take the collision of the pole-type body with the dowel pins into account, the width of the pole-type body as a reinforcing member can be therefore increased to a width of the cavity, and the area of the reinforcing member for supporting the top part can be increased. Accordingly, the structural strength of the front rail can be further enhanced.
The pole-type body may be hollow, and may be a rectangular in cross section but lacks one of four sides. Accordingly, the structural strength of the front rail can be further enhanced owing to such a simple structure while the dowel pin arranged on the printed circuit board can be adequately inserted into the cavity.
A screw plate may be inserted into a cavity partitioned by the front, the top, the rear and the bottom parts, the screw plate having a screw hole allowing insertion of dowel pins arranged on the printed circuit board. Electromagnetic shielding can be therefore enhanced while binding force between the plug-in unit and the front rail can be enhanced by screwing the dowel pin on the screw plate.
The front rail may further comprise an engagement part formed on the top part, the engagement part for engaging the screw plate within the cavity. Insertion of the screw plate into the cavity can be easily performed, and a tip or tilt of the screw plate can be prevented which facilitates the screwing operation of the guide pin.